All flywheels are installed with locking tapers.----They need the correct puller and technique to get them off.----Hurry to your local boat shop and have it pulled.
Not sure why someone would say that is the rectifier !----Most shops take that stabilizer off and throw it away.-----So try this simple test.----Open low speed mixture screws 1/8th turn at a time as that often makes bogging go away.----And are you pushing the key in and holding it in for cold...
On many Mercury motors the clutch dog is spring loaded.-------So if you remove the gear box in neutral it often jumps into forward.----Then you can put control in forward.-----And as always if you understand how they work it becomes much easier.
They never made that style of motor in a 6 cylinder.------Do not confuse this looper style motor with the earlier crossflow inline 6 ( tower of power ) and the smaller 4 cylinder version.------That looks to be a late 1980's model.-----Post the serial # to quickly determine the year.
Having to use the electric primer valve clearly indicates that carburetors need cleaning.----The primer puts fuel into the motor.----This fuel bypasses the carburetor float bowls and metering circuits.
There is one " charge coil " under the flywheel.---It is used to fire both cylinders.-----There is one sensor coil.----It is also used to fire both cylinders.